Operationally and geographically, the department is nominally organized into five borough commands for the five traditional boroughs of New York. Within those borough commands exist nine divisions, each headed by a deputy chief. Within each division operate four to seven battalions, led by a battalion chief and typically consisting of 180–200 firefighters and officers. Each battalion consists of four to eight companies, with a company being led by a captain. He commands three lieutenants and 16–42 firefighters. Last is the unit consisting of the members of the company on call during a given tour, consisting of a lieutenant or a captain plus a number of firefighters depending on the type of unit: three to four on an engine company, five on a ladder company (also known as a truck company), five for a rescue company, five for a squad company, four in a marine company, and six for the hazardous materials company.[5]

On September 11, the battalion chief of Battalion 1 witnessed American Airlines Flight 11 crash into the North Tower of the World Trade Center and immediately radioed a multiple alarm incident. Over the course of the next three hours, 121 engine companies, 62 ladder companies and 27 fire officers were deployed to the scene. All off-duty firefighters were recalled — the first time the FDNY had issued a total recall in over 30 years.[6] In addition to the regular fire apparatus and personnel assigned to the incident, the FDNY also deployed its only Haz-Mat unit, its mobile command center, its field communications unit, all its five rescue units, both of its high-rise units, six of its seven squad units, and one of its two tactical support units.[7]

Fatalities by fire company

Map of FDNY's first-responding firehouses to the September 11 attacks. Circles show the location of the company responding; solid circles mean multiple companies. Rose-colored circles indicate companies with casualties.[8]

The following list is a tally of the fatalities in each company which responded to the World Trade Center:

Rank, Name, Age

The following list provides further details to the preceding list by categorizing the FDNY company with the rank, name, and age (if available) of each casualty. Names without ranks typically denote the rank of firefighter.

Port Authority Police Department

Within minutes of Flight 11's impact, the Port Authority of New York and New Jersey Police Department (PAPD) began deploying officers from the Port Authority Trans-Hudson, bridges, tunnels, and airport commands. The PAPD commanding officer on the scene ordered a full evacuation of the North Tower at 9 a.m., about three minutes before Flight 175 hit the South Tower. At the same time, the PAPD's two most senior officers, superintendent Ferdinand Morrone and Chief James Romito, both arrived separately at the World Trade Center.

Some officers were ordered into the towers to assist with stairwell evacuations, while others helped with evacuations in the plaza and subway station. Superintendent Morrone was last seen helping evacuate tenants on the 45th floor of the North Tower before it collapsed[9] while Chief Romito was in the 31st-floor region with four colleagues helping firefighters.[10] The PAPD lost 37 officers, including Morrone and Romito, and one police dog in the attacks:[11]

Supt. Ferdinand V. Morrone, 63

Chief James A. Romito, 51

Lt. Robert D. Cirri

Insp. Anthony P. Infante, Jr., 47

Capt. Kathy Nancy Mazza, 46

Sgt. Robert M. Kaulfers, 49

Donald James McIntyre, 38

Walter Arthur McNeil, 53

Joseph Michael Navas, 44

James Nelson, 40

Alfonse J. Niedermeyer, 40

James Wendell Parham, 32

Dominick A. Pezzulo, 36

Antonio J. Rodrigues, 35

Richard Rodriguez, 31

Bruce Albert Reynolds, 41

Christopher C. Amoroso, 29

Maurice V. Barry, 48

Clinton Davis, Sr., 38

Donald A. Foreman, 53

Gregg J. Froehner, 46

Uhuru Gonga Houston, 32

George G. Howard, 44

Thomas E. Gorman

Stephen Huczko, Jr., 44

Paul William Jurgens, 47

Liam Callahan, 44

Paul Laszczynski, 49

David Prudencio Lemagne, 27

John Joseph Lennon, Jr., 44

John Dennis Levi, 50

James Francis Lynch, 47

John P. Skala, 31

Walwyn W. Stuart, Jr., 28

Kenneth F. Tietjen, 31

Nathaniel Webb

Michael T. Wholey

Sirius, K-9

New York City Police Department

Temporary NYPD headquarters at 106 Liberty St; set up near the World Trade Center on September 11, 2001.

Several New York City Police Department (NYPD) officers saw Flight 11's impact with the North Tower and immediately reported it to dispatchers. Ten minutes after Flight 11's impact and seven minutes before Flight 175's impact, the NYPD chief of department was en route to the scene and raised the police mobilization to level 4, thereby sending around 22 lieutenants, 100 sergeants, and 800 police officers to the World Trade Center. NYPD personnel were primarily responsible for assisting in evacuations and helping injured civilians.

Two NYPD officers at the World Trade Center site five weeks after the attacks.

Three police helicopters were also deployed to report on conditions and assess the feasibility of a rooftop landing or of special rescue operations. Once Flight 175 had struck the South Tower, another level 4 mobilization was ordered, bringing to almost 2,000 the number of NYPD personnel at the scene. Some were ordered to enter the World Trade Center to assist with the FDNY's evacuations.

The 23 NYPD officers, including four sergeants and two detectives, who died at the scene were:[12]